Defining ‘Substance’ Using Ontological Dependence

I want to propose here an alternative approach to defining ‘substance’: using Fine’s notion of ontological dependence (1995), instead of relying exclusively on grounding (as in this previous post).

A thing x ontologically depends on y iff the essence (real definition) of x includes y.

Fine believes in individual essences –the essence of an individual qua the particular individual it is. I want to set that possibility aside for present purposes and focus exclusively on the essences of the infima species to which an individual belongs. I’ll assume that every particular individual belongs to exactly one infima species, and to “the essence of an individual” will refer to the essence associated with that species.

What does it mean for an essence or real definition to include something? Fine assumes that real definitions are a kind of proposition, in particular Russellian propositions, and so something is included in a real definition just in case it is one of the constituents of that proposition.

I take real definitions to define a class rather than an individual, so real definitions in my view will not typically contain individuals as constituents. They will be more like Fregean propositions. Typically, this will involve some existential generalization. Let’s look at a toy example. Suppose (counterfactually) that a chess set is a substance. The real definition of the substance would include 32 existential quantifiers, one for each piece. The variable associated with one of these quantifiers would have the property of being a white queen predicated of it. If the chess set were a truly fundamental thing, each of these variables would also be associated with the property of being essentially a part of the set.

The real definition of a substance will not include any feature or property that is not stipulated to be a property of the whole substance or of one of its essential parts. Definitions of accidents, in contrast, will refer to some property of the sort of substance in which it can inhere. The definition of a color, for example, will include something like the property of being a surface, even though no surface is or can be part of a color. Similarly, the definition of an essential proper part of a substance will include the predication of the parthood relation between that part and the substance.

S3. A substance is a fundamental particular thing whose real definition does not include the predication of a property to anything other than itself and its essential parts.

This also resolves the problem of origins essentialism as a threat to the independence of substances. The definition of a particular human being is just the definition of humanity in general, and so will not include predicating any property of the person’s parents or the ovum and spermatozoon. It is not essential to human beings to be generated in a certain way—it is in principle possible for a genuine human being to be created ex nihilo, or to be generated by non-human parents. And I don’t think there’s any reason to suppose that God has to be included in any real definition of a creaturely kind.

Arbitrary sums or heaps won’t have a real definition, so they will be automatically excluded. What about non-arbitrary composite things, like bunches, packs, or social clubs? These all have parts that are not essential parts, and their real definitions include predications of properties to such non-essential parts.

A third approach: real definitions and the qualification relation,

Suppose we help ourselves to the qualification relation. Accidents qualify substances: they make it the case that the substance is in a certain way. We could now define substances simply as fundamental particular things that do not qualify anything. Or, better, fundamental things whose nature excludes the possibility of their qualifying anything.

What about proper parts of substances? We need to add a condition that excludes parts of substances from being substances. Or, we could simply exclude things which are essentially proper parts of some other fundamental thing.

S4.1 A substance is a fundamental particular thing whose real definition excludes the possibility of its qualifying anything, and which is not a proper part of any fundamental thing.

S4.2 A substance is a fundamental particular thing whose real definition (i) excludes the possibility of its qualifying anything and (ii) permits the possibility of its not being the proper part of any fundamental particular thing.

In summary, substances, accidents, and parts of substances can all be fundamental entities, in the sense that their actual existence is not grounded by the existence of anything else. Accidents and essential parts of substances are definitionally dependent (asymmetrically) on substances (although not, perhaps, on particular substances).

The relationship between grounding and ontological dependence

Let’s say that a thing is ontologically independent if its real essence does not include any predications to anything but itself and its own essential parts. A thing is fundamental if its existence, essence, and intrinsic character are not wholly grounded by the existence or essence of something else.

Substances are ontologically independent, and accidents and essential proper parts of substances are not. All three are fundamental. So, fundamentality does not entail ontological independence. What about the converse relationship? It’s plausible that every non-fundamental thing is ontologically dependent, since the grounding relationship between the non-fundamental thing and its grounds must be underwritten by its real definition.

	Fundamental	Derivative
Ontologically independent	Substances	[Empty]
Ontologically dependent	Accidents, essential parts of substances, organized groups	Heaps, arbitrary sums

Is the fact that we have multiple definitions of substance, all of which are materially adequate, a problem? No. The category of substance is not a genus, and only genera have real definitions. Aristotle explicitly states in several places that being is not a genus, and since to be a substance is simply to be par excellence, it would follow that substance is not a genus, either. So, our definitions of substance are merely nominal definitions, and having more than one equivalent definition is not a problem.